Direct-access crossbar-switch connector system



July 24, 1962 R. w. HUTTON ETAL 3,04

DIRECT-ACCESS CROSSBAR-SWITCH CONNECTOR SYSTEM Original Filed June 5,1953 6 Sheets-Sheet 2 FROM SELECTOR SWITCH 50 10 25 5 J. PNZE N OE mw w(um. ww 82 32 x3 mw E mmim wz: Him ww 5m I11? n .m II 22 i v a 9m. fl iC3 96 hm. Zww zw? Lw F5558 002 138228 0252i Oh July 24, 1962 R. w.HUTTON ETAL DIRECT-ACCESS CROSSBARSWITCH CONNECTOR SYSTEM Original FiledJune 5, 1953 TO CONNECTOR SWITCH r'-' UNITS REGISTER l l l I FIG. 2 PART2 TENS REGISTER ||zs4seveexol SEQ. DEVICE 6 Sheets-Sheet 3 TO CONNECTOR234 SW'TCHES l234567890 TO CONNECTOR CONTROLLER BX BUSY HM-OPJ July 24,1962 R. w. HUTTON ETAL 3,046,352

DIRECT-ACCESS CROSSBAR-SWITCH CONNECTOR SYSTEM Original Filed June 5,1953 6 Sheets-Sheet 4 PBX TEST RLYS.

UNITS UNITS AUX. 0.0. BUSY T0 couu. swfa P8X RELAYS TO/FROM CONNECTORI600 T0 comi. sw.*2

PBX GROUPING RLYS.

July 24, 1962 R. w. HUTTON ETAL 3,046,352

DIRECT-ACCESS CROSSBAR-SWITCH CONNECTOR SYSTEM 6 Sheets-Sheet 6 OriginalFiled June 5, 1953 ONmTZI ON E llll mdE

TO LINES This invention relates to connector switching systems,particularly as employed in telephone switching systems, being concernedmore particularly with such systems which employ direct-access crossbarswitches. The principal object of the invention is to provide a feasibleand economical direct-access crossbar-switch connector system whichmakes economical use of standardized crossbar switches of relativelysmall capacity and employs a suitable number of them intergrouped toprovide the desired connector-system capacity, one hundred lines in theillustrative example.

This application is a division of our application Serial No. 359,761,filed lune 5, 1953, now Patent No. 2,999,611.

Heretofore, for the most part, direct-access crossbar apparatus employedfor providing connector access to called lines has required thathorizontal multiples between verticals of a given switch be split, oreliminated, to provide the necessary lOO-line access through ten IO-lineverticals, which has required expensive interswitch multipling of the300 conductors comprising the 3-wire switchboard multiples of therespective lines of the IOO-line group. Moreover, the connector systemhas necessitated the use of a separate 10-vertical crossbar switch (or aseparate 10- vertical section) for each connector trunk, thereby tendingto render the system uneconomical as compared with other available typesof connector-switch gear.

According to the invention, the foregoing and other disadvantages areovercome by employing, for a IOO-line connector group, five similarcrossbar switches each having a full horizontal multiple and having asmany verticals as may be required to accommodate the connector trunks,and each having a standardized arrangement for giving any verticalaccess to twenty separate 3-wire horizontal paths, with each pathrepresenting a separate line. The lines of the IOU-line group thucomprise five ZO-line groups corresponding respectively to the fivecrossbar switches.

In the illustrative example, the crossbar switches each has ten 6-wire,2-line horizontals selectable respectively by ten principal selectmagnets, together with twoadditional select magnets (termed upper andlower) which select either the upper three or the lower three conductorsof a selected horizontal. A related feature is that the upper and lowerselect magnets of each switch correspond respectively to the tens-groupdesignation of the called line, and the principal select magnets of anyselected switch correspond respectively to the units-digit of calledlines.

United States Patent A further feature is that, whereas each connectortrunk "ice .1 to of an embodiment of the invention taken in conjunctionwith the accompanying drawings, comprising FIGS. 1 to 5, wherein:

FIG. 1 shows part of the layout of crossbar switches on four 1,000-lineconnector-switch frames for a 4,000-

1 line system;

CONNECTOR SWITCH FRAMES Referring now to FIG. 1, each frame comprises.fifty connector switches, five for each of ten connector groups ofswitches. Of frame CSF1, only the final five switches CS46 to CS-Stl areshown, being those which serve as the tenth connector-switch group ofthe frame (CSFJ) serving the first of the four assumed LOGO-groups ofsubscriber lines, indexed respectively by thousands digits 2, 3, 4, and9, for example. Each of the connector switch frames, CSF-1 to CSF- i,serves a separate one thousand lines. The switches such as CS-46 toCS-Sti, as shown in PEG. 5, are 20 by 20 switches (twenty horizontalsand twenty verticals), in which verticals 1, 2 and 15 only are shown,using the upper and lower select magnet to effectively provide the 20horizontals.

minated on the verticals. Since each switch serves 20 lines, fiveconnector switches serve lines and are arranged in 'a switch group suchas 86-10. Ten such switch groups, 86-1 to SG10, each serving 100 linescomprise a connector switch frame serving 1000 lines. Ofthe ten switchgroups, only the last is shown, and in the switch group only the first,second and last switches are shown.

It has been chosen to provide the one hundred lines in any switch groupwith 15 connectors. These connectors are terminated on the verticals ofthe connector switches which are connected together by conductors incable groups, such as 1fi-l8tl-1 to cable 10-18045 for switch groupSG-1.0. The 1000' lines in any connector switch frame are thereforeserved by connectors.

Referring now to the five connector switches CS-46 to CS-St), it will beobserved that the first switch CS-46 terminates lines having tens digits0 and 1 of the directory number; the tens digit of the numbers of thelines of switch CS-47 being 2 and 3; and the tens digits of the lines ofswitch CS-iifi being 8 and 9. On each of the switches, the tens digit ofleast value is assigned to the upper section of each horizontal.Illustrating, the tens digit 0, 2,

4, 6, and 8are associated with the upper section while tens digits 1, 3,5, 7, and 9 are associated with the lower section of the horizontals,this association being controlled by the tens digit wire assignment tothe auxiliary select magnets.

The units digit of the directory numbers of the lines assigned tohorizontals correspond respectively to the hori zontal numbering asdetermined by the physical location of such horizontals. The lines whoseunits digit of the directory numbers end in 1 are assigned the firsthorizontal, both upper and lower sections; the lines with units digits 2are assigned to the second horizontal; and so forth CONNECTOR 1600Referring now to FIG. 2, parts 1 and 2, the connector 1600 shown thereinwill be described. 1

Connector 1600 includes a test jack TI, 14 relays 1601 Patented July 24,1962 The lines are terminated on the horizontals and the connectors areter-' through 1614, condensers 1615, 1616, and 1617, rectifier 1618,resistor 1619, and magnetic impulse counters SEQ, TR, and UR.

Connector 1600 handles only locally terminated calls which are receivedover its assigned hundreds trunk 121-1, incoming from a selector switch.Connector 1600 performs the following principal circuit functions:

(1) Normally, it supplies idle-indicating battery potential to thesleeve conductor of the attached hundreds trunk;

(2) Upon seizure it removes the idle-indicating battery potential andsubstitutes a holding potential therefor;

(3) It receives and stores three digits, two digits for transfer to theconnector controller to control the extension of a connection to adesired line;

(4) It temporarily seizes the chain circuit of its connector sectionsubject to such chain being idle and thereafter guards the seized chainagainst seizure by any other connector in the same section;

(5) It transfers the two digits of stored digit information to theconnector controller while it has the chain seized;

(6) Upon a signal that the called line is busy, it applies busy tone tothe calling line and frees the seized chain;

(7) When the called line is idle, it applies ringing tone to the callingline; signals the called line; and frees the seized chain;

(8) When the call is answered, it trips the ringing circuit; completesthe talking connection; and reverses the current flow over the tip andring conductors of the attached hundreds trunk;

(9) It supplies transmitter current to both lines;

(10) Upon disconnect by the calling and called line, it clears out andreleases the entire connection by removing holding ground from theincoming sleeve and from the sleeve of the forward connection; and

(11) It provides PBX special services.

The 14 relays (1601 to 1614) of connector 1600 have principal functionsassigned thereto as follows:

Relay 1601 (reverse battery) operates responsive to called party answerand reverses the incoming tip and ring conductors to provide any desiredsupervisory function;

Relay 1602 (line) supplies transmitter current to the calling line;operates when the connector is seized; and restores thereafter undercontrol of the calling device or hookswitch whenever the calling lineloop is opened;

' Relay 1603 (back-bridge) operates over the called line when the callis answered to operate the reverse battery relay, and to supplytransmitter current to the called line;

Relay 1604 (release) is slow-releasing by virtue of a copper sleeveunder its winding; it is operated by the line relay; it remains operatedduring pulsing, but releases when the line relay remains restored for asubstantial fraction of a second;

Relay 1605 (release auxiliary) is operated by the re lease relay andaids in the performance of the release relay functions;

Relay 1606 (ring-cutoff) is operated when the called line answers todisconnect the called line from the ringing current supply;

Relay 1607 (ring-reverse) operates when the station digit dialedcorresponds to the second station on the line to cause ringing currentto be applied to the other side of the line for dividing ringing;

Relay 1608 (ring-trip) is slow-operating by virtue of a copper collarsurrounding the armature end of its core and is operated by the DC. flowin the ringing circuit when the call is answered to open the ringingcircuit and to close the talking circuit;

Relay 1609 (chain) is operated when the stations digit has been dialed;it seizes the chain of the local connector section for the exclusive useof this connector subject to the chain being idle;

Relay 1610 (busy) is operated if the called line is busy to apply busytone signals to the calling line;

Relay 1611 (test) operates when the called line is idle to cut-throngthe tip and ring conductors of the calling line to the tip and ringconductors of the called line;

Relay 1612 (series) is operated by the line relay; is slow-restoring byvirtue of a copper sleeve under its winding; and it remains operatedduring pulsing but restores when the line relay remains restored forsubstantial fraction of a second;

Relay 1613 (series auxiliary) is operated by the series relay and aidsin the performance of the functions of the series relay; and

Relay 1614 (off-normal) operates when any one of the counters isoperated and remains operated until all counters are released.

The three impulse counters, the combined sequence and stations counterSEQ, the tens register TR, and the units register UR of connector 1600have principal func tions assigned thereto as follows:

Impulse counter SEQ (sequence and stations counter) operates at the endof each digit series of impulses to distribute such series to registersTR and UR and to record the stations digit dialed.

Impulse counter TR (tens register) registers the number of impulses inthe tens digit.

Impulse counter UR (units register) registers the number of impulses inthe units digit.

Sequence device SEQ, which actuates its contact set 1 on receipt of thefirst operating pulse, disconnects resistor 1619 as a sleeve-guardingmeasure and completes an operate circuit for the off-normal relay 1614.

DETAILED CONNECTOR OPERATION A detailed operation of connector 1600 willnow be given.

Seizure Connector 1600 is seized by the closure of the calling line loopthrough selector switch 1500 to the tip, ring, and sleeve conductors ofhundreds trunk 1211 to the battery and ground connected windings of linerelay 1602. Relay 1602 operates and closes an operate circuit forrelease relay 1604.

Release relay 1604 operates and at its contacts closes an operatingcircuit for release auxiliary relay 1605.

Release auxiliary relay 1605 operates and at its contacts 1 removes theidle-indicating battery potential from the sleeve conductor and placesground potential thereon; its contacts 2 ground the ring-start wireRI-ST, starting the common ringing apparatus into operation if it is notalready operating; its contacts 4 prepare an operate circuit forring-cutofi relay 1606; its contacts 5 ground common locking wire 1636;its make contacts 6 ground common locking wire 1626; and its contacts 7prepare the release circuit for sequence counter SEQ.

As hereinbefore pointed out, the seizure of the connection isaccomplished during the interdigit period and immediately following thedialing of the hundreds digit of the directory number of the called lineand station, the tens, units, and stations digits are dialed insuccession.

Tens Digit Registration Each time the calling device (not shown) isoperated to transmit a series of circuit interruption impulsesconstituting the tens, units, and stations digits, line relay 1602 isrestored momentarily for each such interruption impulse in a series,comprising from one to ten impulses, depending upon the digit dialed.

Release relay 1604 and release auxiliary relay 1605 remain operatedthroughout any series of impulse-induced restorations of line relay1602.

Series relay 1612 operates promptly upon the first restoration of linerelay 1602, its operate circuit being from the back contacts of relay1602, break contacts 3 of relay 1603, make contacts 7 of releaseauxiliary relay 1605,

. wire 1625, break contacts 4 of sequence counter SEQ,

wire 1632, and break contacts 3 of series auxiliary relay 1613 to thebattery-connected winding of series relay 1612. Upon operating, seriesrelay 1612 locks operated independent of contacts 3 of series auxiliaryrelay 1613. At its make contacts 1, relay 1612 completes an operatecircuit for auxiliary relay .1603 from the ground on grounded wire 1636.

Series auxiliary relay 1613 operates; its make contacts 3 open theinitial operate circuit of the series relay 1612; and its contacts 1prepare an operate circuit for advancing sequence counter SEQ.

With release auxiliary relay 1605 maintained continuously operated, eachrestoration of line relay 1602 delivers an impulse at its break contactsto pulse wire 1625 extending through break contacts 4 of sequencecounter SEQ to pulse Wire 1632, as noted. These ground impulses aretransmitted to the operate winding of the tens register TR through breakcontacts 2 of the sequence counter SEQ and maintain series relay 1612operated.

When line relay 1602 comes to rest, operated, at the end of any digitseries of impulses, series relay 1612 restores after a slight delay andopens the operate circuit of relay 1612 which restores sequentially ashort time later. At such time when series relay 1612 is restored andseries auxiliary relay 1613 is yet operated, the ground appearing onwire 1636 is extended through break contacts 1 of relay 1613 to delivera stepping impulse to sequence counter SEQ.

This stepping impulse which is delivered to device SEQ at the end of thereceipt and registration of the tens digit,

causes both its contact sets 1A and 13 to shift to their alternatepositions. Make contacts 1A close an operate circuit for off-normalrelay 1614; break contacts 1A disconnect idle-indicating battery fromwire 1633 to prevent the reapplication of idle-indicating potential tothe incoming sleeve conductor of the connector before the device SEQ iscleared out; break contacts 1B disconnect the incoming impulse wire 1632from the first tens register TR; and make contacts 13 transfer suchpulsing wire to the operate winding of units register UR.

Units Digit Registration Responsive to the dialing of the units digit ofthe called directory number, a series of circuit interruption impulsesare transmitted over pulsing wire 1625 and are extended through breakcontacts land make contacts 18 of counter SEQ to the battery-connectedwinding of units register UR. At the same time, thesecircuit-interruption impulses are transmitted to series relay 1612 whichoperates as noted and operates series auxiliary relay 1613. The contactsets 1 to 10 of register UR are actuated successively, responsiverespectively to the impulses constituting the units digit.

When line relay 161 comes to rest, operated, at the end of the dialingof the units digit, series relay 1612 restores after a slight delayandthereafter restores series auxiliary relay 1613, as noted. A secondstepping impulse is thereupon delivered to the winding of sequencedevice SEQ from the ground on conductor 1636 causing it to shift itscontact set 2 to its alternate position which opens the operate circuitof units register UR and transfers the pulsing wire to wire 1638extending to the winding of counter SEQ.

Stations Digit Registration Responsive to the restoration andreoperation of the line relay according to the impulses of the stationsdigit, ground impulses are transmitted over wires 1625 and 1638 throughcontacts 2, 3, and 4 of device SEQ to the operate Winding of sequencedevice SEQ: At the same time, series relay 1612 operates followedthereafter by the operation of relay 1613. The make contacts on requencedevice SEQ closed.

The stations digit comprises one or two impulses depending on whetherthe called party is on the tip or ring side of the called line.Therefore, responsive to the dialing of the stations digit, sequencedevice SEQ operates its contacts 3 or 4 depending on whether stationsdigit 1 or digit 2 were dialed. Assuming that the digit 2 is dialed, thesequence device actuated its contact sets 3 and 4 responsive to the twoimpulses of the dialed digit.

Responsive to the third stepping impulse delivered over wire 1636,sequence device SEQ actuates its contact sets 5 which shift to theiralternate position, thereby connecting wire 1628 to Wire 1637.

Shortly after the third stepping impulse from 1636 is delivered to theoperate winding of sequence device SEQ, series auxiliary relay 1613restores and the ground on wire 1636 is extended to wire 1637 which isconnected to the battery-connected winding of the ring-reverse relay1607 through SEQ contacts 5, over wire 1628 and make contacts 3. At thevsametime, ground on wire 1637 is extended through make contacts 4 ofdevice-SEQ to Wire 1621 extending to one side of the chain relay 1609through break contacts on the busy relay and the test relay.

Ring-reverse relay 1607 operates and locks through its make contacts 3to the grounded conductor 1636, and at its make contacts 1 and 2transfer the generatorground wire GEN-6RD from the ring conductor of thecalled line to the tip conductor in preparation for signalling thecalled station on the tip conductor of the line.

As described in the parent application with reference to selectors 1100and 1206', battery from the chain-end wire (in the connector controller,resistor 1749) completes an operate circuit for chain relay 1669providing the selector controller is idle and no other connectors havetheir chain relays operated. I

With line relay 1602, release relay 1604, release auxiliary relay 1605,and ring-reverse relay 1607 operated, sequence device SEQ in position 5,and the tens and units registers TR and UR set according to theirrespective registered digits, an operate circuit is closed for the chainrelay, which operates provided the chain is idle, as noted.

Contacts 3 and 1 of chain relay 1609 prevent any interference by otherconnectors associated with controller 1766 and renders the controllerindividual to the calling tens digit wires and the units digit Wiresextending to V the connector controller and connector switches; and makecontacts 7 connect the secondary-ofimormal wire SON to hold magnetoperate Wire HM-OP.

Testing the Called Line Assuming that the called line was reached bydialing directory nunrber 2101-2 (tens digit 0, units digit 1, andstations digit 2), the tens register TR connects grounded -wire 1630 totens wire T-0 and the units register UR connects ground wire 1631 tounits wire U-ll. As will be described hereinafter, since the tens digitis not assigned to a PBX group, no PBX hunting takes place. The groundappearing on the selected tens and units digit wires is extended to theconnector controller and connector switch thereby causing the tip, ring,and sleeve conductors of the calling connector to be extended to .thetip, ring, and sleeve conductors of the called line by operation of theconnector controller.

As will be described hereinafter, when the hold magnet associated withthe vertical terminating the calling connector operates, it locksoperated through oil-normal contacts to the grounded locking conductor Land at other off-normal contacts ground busy wire BU.

At the time that such hold magnet operates and closes its off-normalcontacts, the sleeve conductor of the called line is extended to oneside of the upper winding of test relay 1611, the other side of suchWinding being connected to ground potential on wire 1626 through breakcontacts 3 of busy relay 1610 and rectifier 1618. Rectifier 1613prevents the ground on wire 1626 from being projected forward on thesleeve conductor so that the cutoff relay associated with the callingline will not be operated prematurely.

Assuming the called line to be idle, the battery potential from thebattery-connected winding of the cutoff relay of called line, causescurrent flow through the upper winding of test relay 1618. Relay 1618operates and locks operated through its lower winding and make-firstcontacts 7; its make contacts 4 ground the sleeve conductor S to operatethe cutoff relay of the called line to prevent answer by the called linefrom causing line finding action to take place; its contacts 2 and 3connect the battery and ground connected windings of the backbridgerelay 1603 to the tip and ring conductors of the called line; its makecontacts 1 apply ring-tone from con ductor RT through tone-couplingcondenser 1717 to the tip conductor of the calling line therebysignalling that ringing has started; its break contacts 5 open theoperate circuit of the busy relay from the grounded busy conductor BU;its contacts 6 connect generator battery lead GEN-BATT to the ringconductor of the called line in series with the winding of ring-triprelay 1608; and at its contacts 8 free the seized chain therebyrestoring the chain relay 1609, freeing the connector controller for usein extending other calls.

Responsive to the restoration of chain relay 1609, its break contacts 2complete the ringing circuit and ringing current is supplied between thetip conductors and ground to signal the desired party; its make contacts5 and 6 remove the ground from the digit wires; and its make contacts 7open the initial operating circuit of the hold magnet associated withthe calling connector. The hold magnet is held operated from the groundon sleeve conductor S.

The Called Line Tests Busy Assuming that the called line is busy, thesleeve conductor of the called line has ground potential thereon fromthe connector in use and this ground appears on the sleeve conductorshort-circuiting the upper winding of test relay 1611, preventing itsoperation.

Responsive to the failure of test relay 1611 to operate, after a slightdelay, the ground potential on the busy lead BU, originating at thecit-normal contacts of the operated hold magnet, is extended throughbreak contacts 5 of the unoperated test relay to the battery-connectedwinding of busy relay 1610.

Busy relay 1610 operates, and at its contacts 1 applies busy tone to thecalling line through the tonecoupling condenser 1617. Its make contacts2 extend the ground potential from make contacts 3 of release auxiliaryrelay 1605, through make contacts 2 of relay 1610 locking it operated.Break contacts 3 of the busy relay 1610 opens the operate circuit of theupper winding of test relay 1611 and at break contacts 4 free the chain,thereby releasing the common equipment.

Responsive to the receipt of busy tone, the calling subscriberdisconnects and the connector and preceding apparatus is restored tonormal.

Called Line Answer Ring-trip relay 1608, whose winding is included inthe ringing circuit does not operate before the call is answered foreach ringer (not shown) on the called line has the usual condenser inseries therewith to block direct-current flow and because the shadingcollar surrounding the armature end of the core, keeps it fromresponding to the alternating ringing current.

In order to permit ring-trip relay 1603 to be operated by direct-currentflow during the application of ringing current (if the call is thenanswered), the applied frequency of ringing current is in series with(superimposed upon) the exchange battery.

When the call is answered at the called station on the called line, theclosure of the usual talking bridge across the called line causesdirect-current flow thereover from the generator battery lead GEN-BATT,operating ringtrip relay 1608. Relay 1608 closes its make contacts toapply ground potential to the battery-connected winding of ring-cutoffrelay 1606.

Ring-cutoff relay 1606 operates and at its make-break contacts 1disconnects ringing tone from the calling line; its make contacts 2 and3 transfer the tip and ring condoctors of the called line from theringing current and extends the talking bridge across the ground andbattery connected windings of back-bridge relay 1603, thereby supplyingtransmitter current to the called line; its break contacts 4 restorering-reverse relay 1607 and its make contacts 5 lock ring-cutoff relay1606 operated to the ground on locking conductor 1626. Ring-trip relay1603 restores, its operate circuit being opened by contacts 2 and 3 ofrestored ring-cutoff relay 1606.

The transmitter current flow through the windings of relay 1603 cause itto operate and at its contacts 1 to remove the ground from thering-start wire RI-ST; its contacts 2 close an operate circuit forreverse-battery relay 1601; and at its break contacts 3 opens thepulsing wire 1625.

Answered Supervision The relay 1601 operates and at its contacts 4maintains an additional ground on locking conductor 1626, rendering theconnector last-party release. Its contacts 1 and 2 reverse the tip andring conductors of the calling line performing any required supervisoryfunction, and at its contacts 3 opens the idle indicating battery supplywire.

During conversation the following relays of connector 1600 are operated:

(l) Reverse-battery relay 1601 (2) Line relay 1602 (3) Back-bridge relay1603 (4) Release relay 1604 (5) Release auxiliary relay 1605 (6)Ring-cutoff relay 1606 (7) Test relay 1611 (8) Off-normal relay 1614Additionally, the three counters SEQ, TR, and UR are held operated byresidual magnetism.

Clearout 7 bridge relay 1603 restores, and restores reverse-batteryrelay 1601. With the restoration of relay 1601, ground is removed fromlocking wire 1626 and all operated relays restore with the exception ofoifnormal relay 1614 which is maintained operated by contacts 1 of thecounters, the counters being held operated by residual magnetism.

At the time when all relays are restored excepting offnormal relay 1614which is maintained operated by contacts 1 of any of the impulse counterdevices, a clearout circuit for all counters is prepared.

Ground potential from break contacts of the line relay 1602 is extendedto wire 1627 through break contacts 3 of relays 1603 and 1605. Thisground is further extended through the back contacts 2 of relay 16111,break contacts 1 of ring-reverse relay 1607, the winding of ring-triprelay 1608, break contacts 2 of chainrelay 1609', break contacts 6 oftest relay 1611 to wire 1635 from whence it is extended through makecontacts 1 of off-normal relay 1614 to battery through the restoringwindings of the counters SEQ, TR and UR in series. The magnetic fluxgenerated by the current flow through the restoring windings is inopposition to the residual magnetism thereby each counter restores.

Responsive to the restoration of each of the magnetic impulse counters,the operate circuit of the off-normal relay 1614 is opened, restoringit. With the restoration of the off-normal relay 1614, the knock-down orrestoration circuit of the counters is opened at contacts 1 and resistor1619 is again connected to wire 1633.

PBX Service As will be described in detail hereinafter, certain lines ofthis exchange may be arranged to provide PBX service, these lines havingcertain tens digits assigned thereto. When calling a PBX group, the tensdigit assigned PBX service is followed by the dialing of the units digit1, else the call will be extended to the called line whether a PBX lineor not. This operation will be described in connection with theconnector controller.

Under conditions when all lines in a called PBX group are busy, groundis returned on the PBX busy lead PBX-BUSY and is extended through makecontacts 1 of the operated chain relay to operate busy relay 1610 whichfunctions thereafter as previously described.

CONNECTOR CONTROLLER AND CONNECTOR SWITCH The operation of connectorcontroller 1700 of FIGS. 3 and 4 and of the associated connectorswitches (FIG. 5) will now be described in detail.

One connector controller is provided to serve the one hundred linesassociated with five connector switches of any switch group. Theconnector controller functions to connect associated calling connectorswith called lines on a one-at-a-time basis. The illustrated connectorcontroller is assumed to be associated with switch group SG- ofconnector frame CSF-l, FIG. 1, of which the first switch is shown inFIG. 5.

Purpose and Arrangement The purpose of connector controller 1700 is tocontrol the crossbar connector switch 1900' in connecting the callingconnectors, such as connector 1600, to called lines.

Connector controller 1700 comprises PBX relays 1750 and connector switchconnector relays 1850 suitably interconnected with each other andassociated with the five connector switches of a switch group, one suchswitch being shown in FIG. 5, to perform the necessary switchingoperation in extending calls to called subscriber and PBX lines.

General Operation On calls starting from the normal cleared outcondition, the general operation of connector controller 1700 is asfollows: 1

Assuming the connector switch 1900 shown in FIG. 5

is connector switch CSS-46 ofswitch group SG-10 of connector switchframe CSF-l, as noted in FIG. 1, the lines having the tens and unitsdigits ending in 01 to 09 and 10 to 19 are served by such switch.

When the calling line has completed the dialing of the directory numberof the called line, assuming that the ground on the selected one of thetens digit wire is transmitted to the winding of the upper or lowerselect magnet of the switch serving the called lines having the tensdigit dialed, such magnet operates and grounds the units lock I Iofi-normal lead UL ON. This lead extends to the windings of theassociated connector switch connect relays,

vthere being five such groups of switch-connect relays,

one group for each switch.

Ground appearing on the units lock off-normal lead UL-ON causes theconnect relays associated with switch 1900 to operate and close theselect magnet and hold magnet leads through to the magnets of theconnector switch.

Ground on the units digit leads from the units register UR istransmitted to the winding of the select magnet associated with thecalled line.

The select magnet associated with the double horizontal serving twolines, including the called line, operates and together with theoperation of either the upper or lower select magnets, selects the onehorizontal that serves the called line. Ground potential is placed onthe secondary-ofi-normal lead SON and is extended to the connector chainrelay contacts and is connected to the hold magnet operate wire HM-OP.

The lhold magnet associated with the vertical terminating the callingconnector operates and closes the tip,

ring, and sleeve conductors of the called line to the tip,

ring, and sleeve conductors of the calling connector.

The off-normal contacts on the hold magnet lock the hold magnet operatedto the noted ground on the lock lead L and place ground on the busy leadBU extending to the connector, as previously pointed out.

If the called line is idle, the chain relay is released thereby removingthe ground from winding of'the operated auxiliary select magnet SMU orSML and from the selected one of the principal select magnet leads SM-1to SM-10. All select magnets are deenergized, but the cross pointsbetween the verticals and horizontals and the upper or lower contactgroup selected by select magnets SMU or SML are held closed by thecontinued operation of the hold magnet.

If the called line is busy, the operation will be similar excepting thatupon operation of the busy relay and consequent restoration of chainrelay, the locking circuit of the operated hold magnet will be opened,thereby returning the switch to normal condition.

PBX Service Certain lines served by a connection switch are adapted forPBX service by extending the sleeve conductor of a line assigned PBXservice to PBX group relays from whence they are used in determining thebusy or idle condition of such lines. Two such sleeve extensions areshown in cable 1735.

Funtional Relay Groups The relays of connector controller 1700 comprisethe i following functions groups: p

1) Relays 1701 through 1704, PBX grouping relays. (2) Relays 1705 to1708, PBX control relays. (3) Relays 1709 to 17 18, PBX test relays. (4)Relays 1801 through 1815, five connector switch connect relay groups,three relays per group.

Detailed Operation the lower select magnet and the lines having the tensdigit I .0 are associated with the horizontals associated with the upperselect magnet. Further, connector switch CSS- 2 is assigned the tensdigits 2 and 3; the third switch is assigned the tens digits 4 and 5;and so torth.

Referring now to FIG. 5 it will be observed that the tens wires T1 to Tare associated with the batteryconnected windings of lower select magnetSML and upper select magnet SMU, respectively.

Assuming tens digit 0 is dialed, then following the operation of thechain relay in the calling connector, ground appears on tens digit wireT-0 and is extended to the battery-connected winding of upper selectmagnet SMU which operates and at its oil-normal contacts extends groundpotential to the units-lock ofi-normal wire UL-ON extending over aconductor in cable group 1037 to the battery-connected windings of theconnect relays 1801 to 1803, these relays being associated with thefirst switch.

Responsive to the ground appearing on the units-lock cit-normal wire,each of the relays 1801 to 1803 operate and close their make contacts 1to 10.

Assuming that the units digit dialed is the digit 1, ground appears onthe units digit wire U-l and is extended over an associated conductorSMC-l in cable group 1737 to contacts 1 on the connect relay 1803.

The ground on digit wire U-1 is extended through make contacts 1 ofrelay 1803 to the battery-connected winding of principal select magnetSM-l, such magnet being associated with the double horizontalterminating the called line.

Responsive to the operation of the upper select magnet SMU and theconsequent operation'of the principal select magnet SM-l, the lowerhorizontal of double horizontal 1-1-1 is selected, such horizontal beingassociated with the called line.

The off-normal contacts of the operated principal select magnet groundthe secondary-otf-normal conductor SON which, as noted, is connected tothe hold magnet operate wire HM-OP through contacts 7 of the callingconnector from whence it is extended through make contacts 1 of theoperated switch connect relay 1801 to the hold magnet wire HM-1extending to the battery-connected winding of hold magnet HM-1901 overconductors in cable group 1836.

The contacts 1 to 10 of relay 1801 and contacts 1 to 10 on relay 1802serve to connect the hold magnet operate wires of each of the callingconnectors associated with any switch group to the hold magnetassociated with the vertical terminating such connector, in thisdisclosure connectors being served by the connector switches of a switchgroup.

Responsive to the operation of the hold magnet HM- 1901, it beingassociated with the vertical terminating calling connector 1600, itlooks operated through its offnormal contacts to grounded lock conductorL and at its off-normal contacts 1, ground the busy lead BU, as noted.

At such time, the called line associated with select magnet SM-l andupper select magnet SMU is connected through the cross points ofhorizontal H1 and vertical V1 to the tip, ring, and sleeve conductors ofthe calling connector and the testing of the called line is performed inthe manner previously described.

Upon finding such line idle, the chain relay is restored therebydisconnecting the secondary-ofi-normal wire SON from the hold magnetwire HM-OP and removing the ground from the tens and units digit wiresT-0 and U-1, thereby permitting the auxiliary select magnet SMU andprincipal select magnet SM-l to restore. At this time, however, theindicated cross points of horizontal H1 and vertical V1, together withthe contacts associated with the upper select magnet are maintainedclosed as long as hold magnet HM-1901 is operated. The initial operatecircuit of hold magnet HM-1901 is opened but it does not restore asground from lock conductor L of calling connector 1600 maintains itoperated.

With the restoration of the principal and auxiliary select magnets, theoperating ground potential is removed from PBX Service It has beenchosen to provide certain ones of the lines whose directory number tensdigit is 1, 2, 3, or 4, for PBX service.

Referring now to FIG. 5, it will be observed that the lines associatedwith the horizontals H1 and H2 and associated with the lower selectmagnet are arranged in a PBX group by connecting an extension of thesleeve conductor to the PBX grouping relays of MG. 3 over conductors incable group 1735. Accordingly, with the dialing of the tens digit 1,thereby operating the auxiliary select magnet SML and the dialing of theunits digit l, thereby operating select magnet SM-l, the PBX relays 1750are operated to extend the call to an idle line in the PBX group.

Gn completion of the dialing of the stations digit of the directorynumber, operation of the chain relay of the calling connector groundsthe tens digit wire T-l and the units digit wire U-1, as noted. Groundappearing on the digit wire T-1 is extended to the batteryconncctedwinding of the auxiliary select magnet SML and at the same time isextended over the tens extension wire "FE-1 to the battery-connectedwinding of the PBX grouping relay 1701.

The lower select magnet SML operates as hereinbefore described,responsive to the grounding of the associated digit wire and at itsoff-normal contacts, operates it associated connector switch connectrelays to connect the select magnet and hold magnet wires to thecoiresponding magnets of switch 1900.

Relay 1701 operates from the ground appearing on the tens extension wireT 13-1 and at its contacts 12 closes an operate circuit for units relay1705 from the ground appearing on the units wire U-1; at its contacts 1to 10, connects the sleeve wires of all lines serving as PBX lines (inthis disclosure S1 and S2 extending to the PBX grouping relays overconductors in cable 1735) to the make contacts 1 to 10 of unitsauxiliary relay 1706; and at its contacts 11 connects battery throughresistor 1731 to locking conductor 1722 in preparation for locking anyPBX test relays that operated.

It will be observed that there is a PBX grouping relay for each of thetens digit extension wires assigned PBX service, each such relayconnecting the sleeves of the lines in their respective PBX groups tothe units auxiliary relay for test to determine their busy or idlecondition.

Units relay 1705 operates from the ground on units digit wire U-l and atits make contacts 1 prepares an operate circuit for units auxiliaryrelay 1706; its make contacts 2 prepare an operate circuit forslow-operating busy relay 1708; and its break contacts 3 open the selectmagnet control wire SMC-l thereby delaying the operation of all selectmagnets until an idle line in the called PBX group is determined.

Units auxiliary relay 1706 operates and at its make contaste 1 to 10connects the sleeve wires of the lines of switch 1900 serving as PBXlines to the ground-connected winding of the PBX test relays.

Assuming switch 1900 has two lines serving as PBX lines and assuming thefirst PBX line is busy, the ground potential on the sleeve conductor ofthe busy lines and the battery potential from the battery-connectedwinding of the cutoff relay of the associated line circuit of the secondline are extended through the closed contacts on the PBX grouping relaysand the contacts of units auxiliary relay 1706 to the ground-connectedwinding of the PBX test relays 1709 to 1718.

Relay 1709 is short-circuited by the grounded sleeve conductor and failsto operate but relay 1710 operates in series with the battery-connectedwinding of the cutoff relay. Relay 1710, at its contacts 1, locksoperated to the locking battery potential on locking conductor 1722;

air lease its make contacts 2 extend ground potential to wire 1721extending to the battery-connected winding of PBX cutoff relay 1707; andits :zrake contacts 3 exercise an order of preference in favor of theline assigned the lowest numbered PBX test relay operated.

Cutoff relay 1707 operates and at its break contacts 1 disconnects thesleeve extensions of the calling line from the PBX test relays; at itsmake contacts 2 disconmeets the operate circuit of the busy relay 1708,this operation being performed before the operate time of the busy relay1708 has elapsed and extends ground potential from make contacts 2 ofunits relay 1705 through break contacts 3 of relay 1709 and makecontacts 3 of relay 1710 to the select magnet control wire SMC-Zextending to the select magnet associated with the second line in thecalledPBX group.

Select magnet SM-Z operates and at its cit-normal contacts grounds thesecondary-ofi-normal wire SON,

.which as previously described, is extended through contacts on thechain relay of the calling connector to operate the hold magnetassociated with the vertical terminating such connector. At such time,the calling line is connected to the called line, such called line beingthe second line of the PBX group, and the connector controller iscleared out as previously described.

In the event that no PBX lines are idle, cutoff relay 1707 fails tooperate and ground from make contacts 2 of units relay 1705 is extendedto: the battery-connected winding of slow-operate busy relay 1708 for asubstantial fraction of a second and causes this relay to operate.

Responsive to the operation of busy relay 1708, ground potential isplaced on the PBX-BUSY lead extending to the calling connector. Aspreviously described, the busy relay of the calling connector operatesand supplies busy tone to the calling line.

Responsive to the removal of ground from the units and tens digit wiresupon extension of the calling line to the called line and the consequentrestoration of the connector chain relay, units relay 1705 restores andthe operated one of the PBX grouping relays restore, thereby completelyclearing out the PBX relays 1-750. Upon the restoration of the principaland auxiliary select magnets on completion of the call extension, groundis removed from the units lock off-normal wire and the operatedconnector switch connect relays are restored.

The connector controllear 1700 is now restored to common use inpreparation for calls from other connectors.

While we have described above the principles of our invention inconnection with specific apparatus, it is to be clearly understood thatthis description is made only l4 horizontals and having verticalmultiples corresponding respectively to the trunks, hold magnetscorresponding respectively to the vertical multiples, principal selectmagnets corresponding respectively to the horizontal multi on -therespective verticals of each switch, control means common to saidtrunks, means controlled over any trunk for operating said control meansin accordance with the tens and units digits of any desired called line,said control means including means for selecting the switch terminatingthe called line according to the called tens digit and for operating theone of the auxiliary select magnets thereof which correspond to suchtens digit, the control means further including means for operating theprincipal select magnet which corresponds to the called units digits andmeans for operating the hold magnet or" the selected switch whichcorresponds to the last said trunk to complete a connection to thecalled line according to which auxiliary select magnet and whichprincipal select magnet have been operated.

2. In a switching system according to claim 1, the said control meansincluding means for directly operating the auxiliary select magnet whichcorresponds to the called tens digit, twenties relays associatedrespectively to said crossbar switches, means responsive to the saidoperation of either auxiliary select magnet of a switch for operatingthe associated twenties relay, and means controlled by the operatedtwenties relay for rendering the principal select magnets of theassociated switch responsive according tothe units digit of the calledline.

3. In a switching system according to claim 2, further means controlledby any said twenties relay for selecting for operation the hold magnetof the selected switch which corresponds to the trunk over which thecall in progress was received.

4. In an automatic telephone system according to claim 3, said trunkshaving respective individualizing relays and means for operating any oneof them to temporarily individualize the associated trunk with the common equipment, the said means for operating :any hold magnet includingcontact means of an operated individualizing relay in series withcontact means of an operated twenties relay, and a by-passingmaintaining circuit for any operated hold magnet.

References Cited in the file of this patent UNITED STATES PATENTS2,038,222 King Apr. 21, 1936 2,672,520 Vos Mar. 16, 1954 2,773,128Hutton et al Dec. 4, 1956 2,816,961 Jones Dec. 17, 1957

